1. Field of the Invention
The present invention relates to a slide fastener which can be used for clothes, bag, and the like, and wherein engaging elements which are independent of each other are mounted to edge portions of fastener tapes at constant intervals, the engaging elements are placed with one upon another, and an engaging male portion and an engaging female portion respectively formed on the upper and lower engaging elements can be engaged with and disengaged from each other in upward and downward directions.
2. Description of the Related Art
As a conventional slide fastener of this type, there is a slide fastener as disclosed in Japanese Patent Publication No. 53-2091, wherein independent engaging elements 1' are mounted to opposed edge portions of a pair of fastener tapes 2' at constant intervals, the engaging elements 1' are placed with one upon another such that the elements 1' can be engaged with and detached from each other in upward and downward directions, the one engaging element 1' is formed with a spherical projection as an engaging male portion 6', the other engaging element is formed with a fitting hole as an engaging female portion 7' to be snap-fitted with the spherical projection, and the engaging elements 1' can be engaged with and detached from each other in upward and downward directions by a sliding movement of the slider 3', as shown in FIG. 27.
In the slide fastener described in the preceding paragraph and shown in FIG. 27, when the engaging elements are placed with one upon another and engaged with each other by the sliding slider, the right and left fastener tapes mounted with the engaging elements are not in the same plane. Therefore, if a tensile load is applied to the right and left fastener tapes, a rotation moment acts on the engaged engaging elements. As a result, the engagement of the elements may be easily cancelled and the elements may be detached from each other. Therefore, the slide fastener suffers from a problem of unstableness.
Furthermore, because tip ends of the engaging elements are exposed in a state wherein the right and left engaging elements are placed with one upon another and are engaged with each other, the tip ends of the engaging elements are caught on other articles when the slide fastener is used, and the engagement of the engaging elements may be easily cancelled and the elements may be detached from each other, thereby causing a fastener chain split.